UCSF

We explore the potential of the ionic products of bioactive glass to induce the up- or down-regulation of genes and transcription factors involved in differentiation and the expression of enzymes and proteins during differentiation. The present study tested the hypothesis that bioactive glass ions enhance the osteogenic potential of human Periodontal Ligament Fibroblasts (hPDLFs) and that a direct connection exists between enhanced gene expression and enhanced matrix protein synthesis.

Experimental bioactive glass (6P53-b) and commercial Bioglass (45S5) conditioned medium was measured for their ion concentrations using inductively coupled plasma mass spectrometry (ICP MS) prior to addition to hPDLF primary cultures. Gene expression was measured using quantitative reverse transcription-polymer chain reaction (qRT PCR). Protein expression (ALP, osteocalcin) was measured using enzyme-linked immunosorbent assay (ELISA). A homogeneous, colorimetric method for determining the number of viable cells in proliferation was also conducted (Promega, Madison WI). Statistical comparisons (p < 0.05 for statistical significance) were made between GCM-treated cells and control-treated cells using two-way ANOVA.

It was observed that increased silicon, calcium, and sodium concentrations were contained in glass conditioned medium (GCM) as compared to control media (DMEM) after 72 h. Cell number continued to increase over 16 days for both treatment groups and control, both in the presence of ascorbic acid and in its absence. Osteocalcin reached its highest expression level at day eight, with enhanced expression in glass conditioned media compared to control. Average alkaline phosphate over-expression was observed at day two and eight compared to control. Gene expression was supported by ELISA results, which showed OC protein expression was at its highest concentration at day sixteen, with enhanced expression in glass conditioned media compared to control. AP was over-expressed on days 8 and 16 compared to control.

These results are significant because to this point, no connection has been made to the enhanced gene expression by hPDLFs exposed to bioactive glass ions and their enhanced downstream matrix protein expression. The introduction of a novel bioactive glass powder to hPDLFs may have the potential to produce mineralized matrices and hence the ability to regenerate bone and cementum within the periodontium.